if the bios pics you posted earlier are from your MB, i think you can. adjusting the 'FSB strap to Northbridge' should give you some additional RAM freq choices. my old X38 MB has 233/266/333/366/400 'straps' or something along those lines. each strap or RAM multi gave me a 3 or 4 RAM freqs to choose from. i can't speek for 45mn chips however LLC on 65nm helped a lot when OC'ing my q6600. i was able to drop the vcore a fair way to keep my 3.7 clock stable (from 1.45v to 1.40v). i however left the power management features enabled (drop to 6x multi and 1.1v when idle). if you're aiming for 4GHz, you may need to adjust the NB volts & monitor the NB temps so keeping this area (NB chip) properly cooled is important. also what MB do you have?